Machine for die casting under pressure



May 21, @940. K-LEBKUCHNER 2,201,906

MACHINE FOR DIE CASTING UNDER PRESSURE Filed May 27, 1958 Patented May2l, 1940 UNlTED STATES MACHINE FoR om oas'rmo UNDER- PRESSURE f Karl Lebkiichner, Granichen, Switzerland, as-

signor to the firm Injecta Aktiengesellscliaft, Teuienthal, Canton of Argovle, Switzerland Application May 27. 1938, Serial No. 210,529 In Switzerland May 29, 1937 Claims.

The invention relates to a machine for die casting under pressure which can be arranged for automatic operation, but may also be hand operated.

Like all machines of this kind also the present machine comprises a hydraulically controlled piston pressing the movable half of the steel mould towards the stationary half by means of a block guided parallelly with the piston.

The invention consists in that said block is loosely coupled with the piston so that block and piston may be moved in relation to each other.

The coupling could be effected in 'a different manner. Most convenient is a hydraulic coupling which may be established or abolished at a given time. It is possible by this manner of coupling to determine the moment for executing this movement. By suitable controlling devices it will be possible to determine the term of abolishment of the coupling and to influence the speed of the movement.

The annexed drawing illustrates an automatic machine according to the present invention.

Fig. 1 represents the machine with closed mould just after a casting operation.

Fig. 2 shows the single members with the mould opened and coreswithdrawn and Fig. 3 shows the position of the different parts at the moment when the casting is expelled.

The.whole arrangement is shown by top views.

The represented machine comprises a frame i 'within which are placed at one end the closing cylinder 2 with a piston 3 and different guides for the rods t required in such machines for guiding the so called block B3. The rods 6 are held fast at the other end of the frame, where is also shown diagrammatically the crucible 5 and the pressure piston which is not represented.

Besides the closing cylinder 2 there are two further cylinders 6, 6' with pistons 1, I. The

. piston rods 8, 8' carry checks 9, 9', I0, Ill and are guided in eyes H, H of block l3. The checks 9, 9', ii], iii may be dispaced on the rods and the cylinders 6, 6' are communicating with a controlled source of pressure liquid.

Piston 3 is connected to the block [3 by means of a hydraulic coupling. This consists of a cylinder I! held fast by the block and provided with a piston M. The inside l5 of the cylinder communicates by an axial bore it of the piston rod with the hind portion ll of the mould closing cylinder 2. A cut off valve l8 controls the bore IS, the purpose of which will be explained further The useful area of the cylinder inside I5 is smaller than the useful area of the hind portion ll of the cylinder and this latter is smaller than the useful cylinder area it of the fore part. Therefrom follows that with the same pressure at It and H the piston 3 will move from the left to the right if it be supposed that the pressure at I9 be relieved by opening a drain.

The piston rod 3 carries behind cylinder 6! rings 20 which partake in the movements of the piston and to which the rods 2i are secured. These rods connect piston 3 with an intermediate piece 22, which is rigidly attached to the guide tube 23 and carries at its back end adjustable rings 24. The guide tube 23 is slidably held in a longitudinal direction within block it and carries the core plates 25 to which the cores 25 are attached. These according to Fig. 1 are extended into the die casting. It is easily seen from the drawing that the movements of the piston 3 are transmitted by means of the rods 20, the intermediate piece 22 and the guide tube 23 to the cores. These latter participate therefore in all the movements of piston 3.

Block 83 carries also two hollow rods it having checks 29 and being guided alongside of cylinder 2 in the same framing. These rods support an expelling frame 313 and carry inner rods 38 provided at their hind ends with threads and with nuts 32, by which by'means of clamps 33! the expelling plates carrying the expellers 3d are attached to the expelling frame 3d. Said hollow rods 28 are always kept in a determined position in relation to block itby means of a spring 3 3 cooperating with checks 35, 86. If however the checks which are adjustably held by the hollow rods 28 contact with the frame, block it: will be able to execute a movement relatively to the rods 28. At this moment also the expellers 38 will become effective which are fast to the expelling plate. The represented machine is operated as follows:

In the position shown in Fig. l the casting operation has been done. In space it of the closing cylinders i still remains liquid under a very high pressure. Piston 3 is maintained in its position on the left. Head 39 by means of cylinder I! has taken along block it when the mould was closed and has pressed block is together with core plate, expelling plate and movable half of the mould to the left. The movement has been arrested by the stationary half of the mould and the metal flows now from the crucible 5 into the free space left between the two halves of the mould. The cylinder portions l5 and H are filled with liquid of constant pressure. Their common eflect however is not able to compensate the effect of the pressure inside space it.

Also into the cylinders 6, 5 pressure liquid has been introduced. After the closing of the form has been completed however, a valve in this admission conduit will be closed so that the enclosed liquid volume cannotescape.

Now the opening of the mould begins, also the separating of the two mould halves, the withdrawing of the cores and the expelling of the the casting sticks to the core.

' first movement upon 2 ready casting. To this end at first the pressure in space II is relieved by permitting the draining of the liquid therein enclosed. At this moment the constant liquid pressure in space I! and in space I! becomes eifective. The useful piston area in space I! is considerably larger than the area in space I! and thus piston 8 will move to the right. The liquid enclosed within space l5 plays for at present the roll of a hydraulic cou-. pling, so that cylinder l2 and the block is coupled therewith follow the movements of the piston 3. All devices carried by the block follow with it until the eyes II, II of the block make contact with the checks 9, 8'. I

At the same time the checks 29 on the hollow rods Ilare stopped by the frame 1. This position is shown in Fig. 2.

From the latter ions inside cylinder 6, 6' having stopped the rods I, U have rendered the checks 9, 9' eillcacious. Block I: cannot advance further but the pressure in chamber l'l continues and remains further effective and prevails over the .pressure in chamber IS. The liquid in this chamber returns through the bore into chamber l1 and thus a relative movement has taken place between piston head 39 and cylinder l2. This movement is transmitted through rods 2! to the guide tube "and to the core plates with cores 26. The latter are withdrawn and at this moment the adjustable rings become adjacent to cylinder i2.

Then the drain of the liquid cushion within cylinders i, 6' will be permitted, so that the liquidpressure in chamber ll produces a further movement of piston 3. This movement is transmitted by rings 2! to block l3. But, because the checks 29 remain already at the end of the the frame, every movement of the block will produce a relative movement between the expelling frame 30 and expellers 38 at the end of the rods 28 and the movable half of the mould held by the block.

In Fig. 3 the position of the-different machine parts at the end of this movement is shown.

Then the ready casting will be expelled from the mould and dropped into a container. After this a high liquid pressure is again produced in chamber l9. Piston 3 will move to the left, lib-, crates the different checks, permits the release of spring 34 and likewise the refilling of the liquid cushions within cylinders 6, B. The movable half of-the mould comes again into contact with the stationary half and a new casting may be operated.

If large cores have to be withdrawn the liquid in chamber l5 must be pressed out and then the communication between this chamber and chamber II will be interrupted by closing the stop valve l8. Thereby it has been attained that in chamber [5 no pressure is present to resist the pressure in chamber l1 and thus the whole pressure in chamber II will be available for the withdrawal of the cores. The connection between piston 3 and block I! and therefore the moving of the latter towards the checks 9, 9' is no more affected with large cores by the hydraulic coupling l5,.but simply with the power by which This power is with large cores so considerable that it sufilces for opening the mould and to withdraw the block unto the checks 9, 9 whereupon the cores will be withdrawn with all the pressure of chamber I'I. 4

From the above it may be seen, that the machine comprises a hydraulic coupling between it is seen that the liquid cushmould carrier and piston as well as also hydraulically controlled means used when the cores have to be withdrawn. By using these particular devices a much higher number of casting operations than with any other known machines are possible. The coupling and uncoupling and the operating of the checks requires no time in a casting operation. By this instance the present machine is above all adapted for an automatic operation. The hydraulic coupling and the hydraiHic buffersrepresent a combination permitting the withdrawing of the cores of the mould carrier during the opening of the mould in the opening direction and to bring the cores again into their casting position without using further sources of pressure liquid than those afforded by the moving mould carrier.

What I claim is: r

1. In a machine for die casting under pressure, a frame, a mould comprising a stationary and a movable half, a slidably arranged block carrying said movable half, a first cylinder secured to the frame and containing a hydraulically operated piston for closing and opening the mould, a piston-rod attached to said piston, a second piston secured to said piston-rod, a core plate rigidly connected with said piston-rod with the help of suitable connecting-means, a second cylinder secured to said block and containing said second piston, a pressure medium in said second cylinder and on one side of said second piston, a conduit for permitting the volume of said pressure medium to be increased and diminished, thus allowing a relative movement between said core plate and said block.

2. In a machine for die-casting under pressure according to claim l, said conduit formed as a bore in said piston-rod and connecting the one portion of the first cylinder with that portion of the second cylinder, which contains the pressure medium, and checks connected by suitable means with the frame and adapted to stop the block, whereby, after said stopping, the relative movement between block and core plate can begin.

3. In a machine for die-casting under pressure according to claim 1, a valve in said conduit,

adapted to cut off the inflow of the pressure I medium into the second cylinder.

4. In a machine for die-casting under pressure according to claim 1, said conduit formed as a borein said piston-rod and connecting the one portion of the first cylinder with that portion of the second cylinder which contains the pressure medium, a valve in said bore,,adapted to cut oil the inflow of the pressure medium into the second cylinder, and checks connected by suitable means with the frame and adapted to stop the block, whereby,after said stopping, the relative movement between block and core plate can begin.

5. In a machine for die-casting under pressure according to claim 1, further cylinders mounted on the frame and containing hydraulically operated pistons, piston-rods secured to said pistons. checks on said piston-rods, adapted to stop the block, an ejecting-device elastically connected with said block, further checks connected with said ejecting-device and adapted to bear against the frame, thus permitting of a relative movement between block and ejecting-device, and other checks on said piston-rods adapted to stop the relative movement between block and ejecting device.

' K. LEBKUCHNER. 

